A popular term for an unidentified police officer who felt compelled to draw a chalk line–which now only appears in fictionalised crime scenes portrayed on TV or in the movies–around the body in a crime scene, believing that doing so was correct protocol–when in fact he just committed the mother of all crime scene errors.
The same mystery cop doesn’t hold up his* hand when irate scene investigators try to find out who (the clown was who) contaminated the scene.
*I should probably also say her, but I’m told women never make mistakes. The name of course derives from the tooth fairy, Tinker Bell and other mythical fairies, who no one ever sees, but whose effects are evident.
Reference VJ Geberth, Practical Homicide Investigation, 1996